As one conventional air conditioner, there is an air conditioner used to air condition a building or the like. Such an air conditioner is mainly disposed with a heat source unit including a compressor and heat source heat exchanger, a utilization unit including a utilization heat exchanger, and a gas refrigerant pipe and a liquid refrigerant pipe for interconnecting these units.
In such an air conditioner, when performing work to update the air conditioner in an existing building or the like, sometimes the gas refrigerant pipe and the liquid refrigerant pipe (called “existing refrigerant pipes” below) interconnecting the heat source unit and the utilization unit are appropriated in order to shorten the work period and reduce costs.
However, acid components generated by deterioration of the working refrigerant and refrigerating machine oil during operation of the air conditioner prior to update, and acid components stemming from moisture ingressing from the outside during the work of updating, remain inside the existing refrigerant pipes appropriated during the work of updating the air conditioner in a state where the acid components are mixed in with the refrigerating machine oil (called “existing refrigerating machine oil” below) that was used in the air conditioner prior to update. Such acid components compromise the reliability of devices that configure the air conditioner, such as the compressor, because the acid components deteriorate the working refrigerant and refrigerating machine oil filling the updated refrigerant circuit, so it is necessary to remove the acid components during test operation that is performed before normal air conditioning operation.
In order to counter this, trapping and removing moisture ingressing from the outside into the refrigerant circuit by disposing a dryer in the refrigerant circuit and performing refrigeration cycle operation during test operation after the air conditioner has been installed in a locality and maintenance has been performed is being considered (e.g., see Japanese Patent Publication No. 9-236363).